Morse code translator

Type text on the left to get Morse on the right. Going the other way, separate letters with spaces and words with a slash, the format the converter itself produces.

The controls underneath play the message rather than printing it. Play sound sends it as a tone. Flash light blinks it in the lamp beside that button, small and capped at three flashes a second so it's safe to watch. Speed sets how long one unit lasts and Tone sets the pitch. The player beside Download .wav lets you replay and scrub through the audio, and the button saves it at whatever you've chosen.

The alphabet chart is further down. Print chart puts it on a sheet of its own with nothing else on the page, the address and a code to scan under the letters, which is the version worth pinning up.

Everything is built on one unit of time. A dot lasts one unit, a dash three. Gaps run one unit inside a letter and three between letters. Seven between words. The tempo can change but those proportions can't, which is how two operators at different speeds still understand each other.

Speed is measured against the word PARIS, whose dots, dashes and gaps come to exactly 50 units. Send PARIS 20 times in a minute and you're sending at 20 words per minute.

Samuel Morse and Alfred Vail built the code for the electric telegraph in the 1830s and 1840s. The international version settled in 1865. E, the commonest letter in English, is one dot, while Q and Y run to four symbols. Morse gave the shortest codes to the letters operators would send most.

The Titanic's operators sent the old distress call CQD and the new SOS on the same night in 1912, and the newer one stuck. The French Navy stopped using Morse on 31 January 1997 with a line nobody has improved on: "Calling all. This is our last cry before our eternal silence."

Amateur radio operators still use it. So do aviation navigation beacons, which identify themselves in Morse on a loop to anyone tuned in.

A telegraph key has two states, on and off, and binary answers the same question inside a computer with two digits instead of three durations.

For alphabets rather than signals, runes and Ogham swap the letters and keep the words. And if you've been handed something unreadable that might not be Morse at all, the cipher identifier will tell you.

Ages 8 and up, about 30 minutes. Teach the dots and dashes with sound first: use the play button above to hear SOS, then let students tap messages on the desk to a partner, who writes down what they hear. Short words such as HI, YES and NO work best to start.

Take it further: talk about why E is a single dot and Q is long, which is about how often letters are used, and compare it with the letter counts in a paragraph of their own writing. The Morse code chart prints for the wall.